Here are the article in HFN &RR that inspired me to buildning the DCH (Decca Corner Horn)

As I hade low expectations I built them in 11mm OSB, now I have found veneered ply at quite good price. So perhaps, perhaps!

The Voight pipes I have seen have had a cross section area at the closed end from 0 to perhaps 50% of the surface area of the drivers cone. In this case it is 150%, then the negative taper around the driver and the final constriction of the opening that is both a 19mm high slot around the sides and read but also a 100mm long facing the flat front? I have been told that this DIY version is a simplifacation of the commercial Decca speaker, but as far as I can tell the images of decca speakers in the net looks like mine,

They are quite wide and high but as they are shallow and fit in a corner or flush to a wall they are less dominating than sheer size suggest.

I will get back with posts on various 8" drivers, With Fr from 30 to 100 Hz and Qts from below 0.3 to above 1.0. The DCH was intended for a fullrange driver but one could equally well use a conventional 8" unit and tweeter/tweeters. Perhaps even a 10" unit.

The Decca corner horn is the second to the left.